Conventionally, a connector which is comprised of a socket and a header is provided for electrically connecting between circuit boards, for example, an FPC and a hard board. A conventional connector mentioned in, for example, Japanese Laid-Open Patent Publication No. 2002-8753 is described with reference to FIGS. 7A to 7C, FIG. 8, FIGS. 9A to 9C and FIG. 10.
As shown in FIGS. 7A to 7C and FIG. 8, a socket 50 has a socket body 51 which is formed into a substantially flat rectangular parallelepiped shape by resin molding and a plurality of socket contacts 60 which is arranged on two lines along longitudinal direction of the socket body 51. Seen from front, a protruding table 53 of substantially rectangular parallelepiped shape is formed in a center portion of the socket body 51, and a plug groove 52 of substantially rectangular shape is formed between the protruding table 53 and each side wall 54 in longitudinal direction and each side wall 56 in widthwise direction.
The socked contact 60 is formed by bending a band metal into a predetermined shape by press working. A first contact portion 61 which is to be contacted with a header post 80 (referring to FIGS. 9A to 9C and FIG. 10) is formed at a first end portion of each socket contact 60 facing the plug groove 52. A first terminal portion 62 which is to be soldered on a conductive pattern of a circuit board is formed at a second end portion of the socket contact 60 positioned outward of the side wall 54. Each socket contact 60 is press-fitted after resin molding of the socket body 51.
On the other hand, as shown in FIGS. 9A to 9C and FIG. 10, a header 70 has a header body 71 which is formed in a shape of substantially flat rectangular parallelepiped by resin molding and a plurality of header post 80 which is arranged on two lines along longitudinal direction of the header body 71. An engaging groove 72 of substantially rectangular parallelepiped shape with which the protruding table 53 is engaged is formed at a position facing the protruding table 53 of the socket body 51. Flange portions 74 are formed on side walls 73 of the header body 71 so as to protrude substantially perpendicular to the side walls 73 from edges on rear face side (circuit board side) of the header body 71. Furthermore, engaging protrusions 75 which are to be engaged with key grooves 55 provided on the protruding table 53 of the socket 50 are formed at four positions on wall faces of the side walls 73 in side of the engaging groove 72 so that impact applied while the socket 50 and the header 70 are connected is dispersed.
The header post 80 is formed by bending a band metal into a predetermined shape by press working. A second contact portion 81 which is to be contacted with the first contact portion 61 of the socket contact 60 is formed at a position of each header post 80 along an outer surface of the side wall 73. Furthermore, a second terminal portion 82 which is to be soldered on a conductive pattern of a circuit board is formed at an end portion protruding outward from the flange portion 74. Each header post 80 is integrally fixed on the header body 71 by insert molding while the header body 71 is molded by resin.
The socket 50 and the header 70 are mounted so that the first terminal portion 62 of each socket contact 60 and the second terminal portion 82 of each header post 80 are respectively soldered on conductive patterns of circuit boards. When the header 70 is engaged with the plug groove 52 of the socket 50, the protruding table 53 of the socket 50 is relatively engaged with the engaging groove 72 of the header 70, and the first contact portion 61 of the socket contact 60 contacts the second contact portion 81 of the header post 80 with elastic deformation. As a result, a circuit board on which the socket is mounted is elastically connected with a circuit board on which the header 70 is mounted.
Generally, when the plug groove 52, with which the header body 71 is engaged, is formed on the socket body 51, mechanical strength of the socket body 51 becomes weak so that it is easily deformed. In the above-mentioned conventional connector, in order to increase the mechanical strength of the socket body 51, the protruding table 53 is provided in the inside of the plug groove 52, and the engaging groove 72 which is to be engaged with the protruding table 53 is formed on the header body 71. Therefore, the conventional connector has a problem that dimensions in widthwise directions of the socket body 51 and the header body 71 becomes larger by the dimension of the protruding table 53.
Furthermore, a curved surface portion 83 is provided in the vicinity of the front end of the header post 80 so as to contact the socket contact 60 with the header post 80 smoothly, but it is necessary to provide the engaging groove 72 on the header body 71, so that it is difficult to take a configuration that a front end of the curved surface portion 83 is hooked on the header body 71. Therefore, for example, when the header 70 is taking out and putting in for the socket 50 obliquely, the header body 71 may be deformed, and the front end of the curved surface portion 83 of the header post 80 may be raised and come off from the header body 71.
Still furthermore, as for the first contact portion 61 of the socket body 61 (SIC: 60 is correct), a distance between a pair of first contact portions 61 of the socket contacts 60 facing each other is established to be narrower than a distance between a pair of second contact portions 81 of the header post 80 which are contacted with the pair of socket contacts 60 so that contacting pressure is generated in a state of connection of the socket 50 with the header 70. While the socket 50 is connected with the header 70, a free end of each socket contact 60 contacts with the curved surface portion 83 of the header post 80, slides on the curved surface portion 83 and moves to the second contact portion 81. However, when the curvature radius of the curved surface portion 83 is made too small, the free end of the socket contact 60 may not be slid on the curved surface portion 83 smoothly, and the free end of the socket contact 60 may be scratched, so that the first contact portion 61 may be deformed due to buckling. Accordingly, there is a limit to reduce the curvature radius of (outer face of) the curved surface portion 83 of the header post 80. Since the thickness of the side walls 73 of the header body 71 is affected by the curvature radius of the curved surface portion 83 of the header post 80, there is a limit to reduce the thickness of the side walls 73, in other words, the width of the header 70.
By the way, in the connector used for a compact electronic equipment such as a mobile phone, the pitch of the socket contacts 60 and the header posts 80 is very narrow as, for example, 0.4 mm extent. In addition, a connector further downsized is demanded for further downsizing the electronic equipment. On the other hand, a dimension of the connector in longitudinal direction (arranging direction of the socket contacts 60 and the header posts 80) depends on the pitch and the number of the socket contact 60 and the header post 80. In addition, there is a limit to make the pitch of the socket contacts 60 and the header posts 80 narrower because of securing the distance for insulation. Accordingly, the downsizing of the connector can be achieved by reducing the dimension in widthwise direction thereof. Therefore, when the dimension of the connector in widthwise direction is made shorter by eliminating the protruding table 53 of the socket body 51, the mechanical strength of the socket body 51 and the header body 71 becomes a problem. It, however, can be solved by inserting or press-fitting reinforcing members into the socket body 51 and the header body 71.